What is the archived-expanded-entitlements.xcent
file ?
What is the use of this file in an iOS application?
Basically, the xcent file is a list of entitlements that the app has requested. Since Xcode 6, the entitlements list is also embedded in the app bundle as the xcent file. This file is important when it comes to submitting to the App Store and provides more helpful error messages when provisioning errors occur.
If you want more info, here is a good in-depth article on code signing and provisioning.